Seismic design and retrofit using Shape Memory Alloys

This study evaluates the use of Shape Memory Alloys as passive dampers in applications in buildings and bridges. Using the shape memory characteristic of Nitinol, an innovative steel partially restrained connection with SMA tendons is tested. The connection is subjected to several loading cycles at large rotations, exhibiting no strength degradation. After completing a series of testing cycles, the tendons were heated through their transformation temperature and recovered their previous undeformed shape. The connection was retested and displayed nearly identical performance. Using the superelastic property of Nitinol, SMA restrainers are tested for application in bridges. Analytical studies show that these devices, used at intermediate hinges and abutments are effective in limiting the relative hinge displacement and overall demands on piers.